No, I've seen coachwhips many times and in my opinion, that is either a gopher snake or a rat snake. It's too thick and a coachwhip moves differently and generally won't stand it's ground like that unless cornered, preferring to bolt rather than fight. In that type of terrain, a rat snake or gopher snake won't hesitate to climb a tree to escape, and that snake didn't look very skilled at it. A coachwhip would have been half way up that tree in a matter of seconds. Anyway, look closely as the snake tries to climb. For a second there, you can see the snake is yellowish in color with black markings, like a gopher snake. In the beginning, it looked striped, and very well might be just laterally, but dorsally, looks like blotches. Looks like perfect hunting grounds for a gopher snake, but it looks like the hunter became the hunted!